Photoresist materials on metallic substrates having either positive acting or negative acting photoresist layers are well known in the art. U.S. Pat. Nos. 3,395,016; 3,639,185; 3,469,982; 3,782,939; and 4,193,797 as well as Canadian Pat. Nos. 976,352 and 976,353 disclose various imaging materials of this type.
Some of these patents disclose aluminum or aluminum coated substrates as the image density layer, but aluminum has been a particularly difficult material to use in such imaging systems. As noted in U.S. Pat. No. 4,008,084, aluminum is recognized as being quite difficult to etch owing to its tendency to form aluminum oxide which is not readily attacked. U.S. Pat. No. 4,008,084 attempts to solve the problem by mixing particles of iron in the aluminum to provide a more readily etchable material.
Other references attempt to avoid using aluminum at all, providing a metal coating layer of molybdenum, bismuth, chromium, or tellurium instead. These metals have their own problems associated with them, including cost, limited quantities available, and/or toxicity.
Furthermore, when using these systems of the prior art, it has usually been necessary to use one solution to remove the photoresist, an intermediate wash bath, a second solution to etch the metal layer, and then a final wash bath.